alt Hacker NewsI don't think a DAG makes sense as a model here. I've always likened terraform apply to setting what would be called a "waypoint" in robotics, or a "keyframe" in animation. The system doesn't immediately change state to the new state all at once, but it starts to tend towards the new desired state.
While the intermediary states might form a graph when considering different subsystems, the desire to move towards a given state should probably appear serial over time. When you make a terraform transaction, you have to coordinate in a serializable way with everyone else managing the desired state, even though the actual state will be messy along the way.
Your Terraform/Tofu code is a graph. Resources are nodes and the dependencies between them are edges, so a graph is a very natural and useful representation of infrastructure. There are well-understood algorithms for transitioning a graph between two representations that can be leveraged as well. I think how you describe representing state would work fine, but a graph works quite well and is more natural for the types of operations we want to perform on the graph.